Brick grease composition



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Patented Apr. 1, 1952 BRICK GREASE COMPOSITION Lorne'W'. Sproule and Laurence F. King, Sarnia, Ontario; Canada; assignors to Standard Oil Development Company, a corporation of Dela--- ware No Drawing. ApplicationNovember 28, 1950, Serial No. 198,022

The present invention relates to a grease composition for high temperature service. It relates in particular to a hard firm grease of block or brick type which iscompounded so as to afford a maximum of lubrication with a minimum of leakage under severe operating conditions, e. g., conditions of unusual temperature, and/ or in the presence of moisture or water vapor, etc.

In the prior art, a large number of so-called block or brick grease compositions have been proposed, and a number of themhave been used successfully in some applications. These greases are characterized by a firm or relatively hard consistency, usually obtained by relatively high soap content- Greasesof this type are frequently used to lubricate large relatively slow moving journals operating under various load conditions, often very heavy load conditions. Such greases have been used in various industrial machines operating at elevated temperatures, especially where large cylinders or rollers are mounted in plain journals, as in drying machines for textiles, and in paper making machinery Where the journals'of large drums, for example, of hot drying or calendaring drums or rollers, and the like, heated with hot water or steam, are to be lubricated.

In the paper manufacturing industry in particular, it is a common practice to lubricate the heavily loaded journals, normally supported in a half bearing, by placing bricks or blocks of very hard grease in direct contact with the journals. These greases have high soap content but the lubricating oil is usually of a moderate viscosity. As the journals rotate, the grease is worn away to leave a light lubricating film of the oil on the journal surface. Various attempts have beenmade to control-lubricant. consumption and lubricating eificiency by adjusting the hardness of theblock. This has been doneby varying the soap content of the grease, so that just enough grease is carried away by the journal to provide lubrication without causing excessive consumption of the lubricant. In some cases filler materials such as sodium carbonate, potassium silicate, graphite, cotton fibers, wool Waste, sulfur, sodium chloride, and sodium bicarbonate have been used in block greases to harden them and control consumption. These sodium and potassium salts of course are objectionable where moisture is prevalent, as in paper mills. They tend not only to be washed away but they also cause serious metal corrosion.

A major problem encountered in lubricating large journals of heavy machinery operating at high temperatures is leakage of grease. This is particularly objectionable in machinery for 6 Claims- (Cl. 252-41) making or finishing paper and textiles. In fact, a grease leakage in excess of about 0.08 to'0.1 pound per hours per bearing in paper machinery of standard type cannot be tolerated. At the same time, if the grease has been made so hard that it will not leak appreciably, it is likely to have deficient lubricating properties. Experience indicates that there must be some moderate consumption of the grease for adequate lubrication. Consumption is ordinarily controlled by grease hardness. In large paper machines, e. g., where drying drums are steam heated to temperatures of 260 to 275 F., a total grease consumption less than about 0.1 lb. per bearing per 100 hours appears to give inadequate lubrication, resulting in excessive bearing wear. A consumption rate of 0.15 to 0.4 lb. per 100 hours per bearing appears to be about optimum. sofar as bearing protection is concerned but such consumption results invariably in excessive grease leakage in all known prior art compositions. Moderate consumption, with very little leakage is an objective hitherto unattained.

In a recent patent to Smith et al., No. 2,442,828, it is suggested that block greases which are not consumed rapidly but may provide adequate lubrication at high temperature may be prepared by combining certain high melting waxes, e. g.', carnauba wax, with greases of high soap content. See also the-patent to Smith No. 2,383,656, wherein the method of testing for grease consumption, as employed in the later Smith patent, is described in detail. The Smith composition has the feature of requiring appreciable quantitiesof. relatively costly wax,,but aside from this, the temperature range over which the wax is efiective to control consumption appears to be quite limited. U. S. Patent, No. 2,442,828,, further suggests that sodium bicarbonate may be .used to reduce high temperature consumption. See British patent, No. 9'78 of 1878, for an. earlier use of sodium bicarbonate and waxesin block grease. U. S. Patent 2,413,121, to Swenson, suggests the addition of rosin or rosin oil.

The present invention resulted from various attempts made to secure proper lubrication of standard paper mill drying journals, without excessive lubricant leakage, but with sufficient lubricant consumption for good. lubrication by selecting base oils of specific viscosity, along with an appropriate soap content. In testing such compositions, and in arriving at the present invention, standard paper mill journals mounted in half round bronze hearings were employed to test adequacy of lubricating film and rate of'consumption. These bearings and journals normally operate at temperatures between about 200 and 275 F. It was found that greases containing oils of moderately high viscosity and low soap contents, gave very satisfactory lubrication but showed considerable leakage after extended operation. On the other hand, the use of larger proportions of soap to reduce leakage resulted in inadequate lubrication. As previously suggested, in paper mill and textile mill operations, excessive leakage of grease from bearings is highly objectionable on several grounds: (a) contamination of the paper, or textile, (b) fire and other hazards to personnel, and increased maintenance costs due to the necessity for frequent cleaning of bearings. On the other hand, greases made from oils of lower viscosity, thickened with a larger proportion of soap to obtain the desired block grease consistency, gave poor lubrication, although they showed a lower amount of leakage.

' According to the present invention, adequate lubrication without excessive leakage may be secured by combining a relatively very light lubricating oil component, one which evaporates Even though operating temperatures of 200 to 275 F. are far below the boiling points of the more volatile parts of the oil, the fact is that greases using only the lighter oils do evaporate to a very serious degree when exposed in a thin film such as occurs between the journal and bearing under the conditions normally encountered in paper mill driers, and the like. Examples A and B of Table I were typical of prior :1; art block greases.

Another series of tests were carried out at various temperatures, beginning at 225 F. with a journal surface speed of 33 ft. per minute. Four different compositions, C, D, E and F were tested. Subsequent additional tests were made differing viscosities. It should be carefully compared with Examples H and J where the blended oils were of comparatively very light and very heavy fractions. The difference is striking.

TABLE II Formulae and evaluatzon of brzck or block greases Mineral Oil Laboratory Evaluation Evaporation Per Cent Con- Grease Soap W100 Test, S eed sumpa Per Lubrica- S S U Type V. I. Pen. Alk. Temp. i tion, f Gentoi tion, Film a F. lbs/100 1bs./l Total Thickness rs. hrs. Consumptlon 11. 5 100 narrow cut 89 neut. 225 33 0.17 0.025 0.14 82 Poor. 11.5 3300 do 78 neut. 225 33 0.11 0.10 0. 008 7 Excellent. 11.5 36]. Wide cut (blend of 100 45 71 neut- 225 33 0.13 0. 04 0.08 Good.

and 3,300 vise.) l1. 5 350 narrow cut 45 73 neut- 225 33 0.135 0. 00 0.04 33 Do. 11. 5 361 wide cut (blend of 100 45 71 neut. 250 33 0. 30 0.14 0. 15 47 Do.

and 3,300 vise.) 11. 5 350 narrow cut 45 73 neut. 250 33 0. 29 0. 22 0. 07 23 Do. (apprm Blend of about equal parts of 45 V. I. 0. 12. 270. 33 0. 32 0.16 0. 134 42 Do.

medium light and med. heavy (214 S. S. U. 100 and 900 S. S. U. 100 F.) Average vis. 400 S. S. U. at 100 F. H 25 (approx) Blend of about equal parts 100 S. S. U. 76 0.10 270 33 0. 34 0.075 0. 20 60 Excellent.

100 F. and 2600 S. S. U. 100 F., 45 V. 1. Av. vis. 400 S. S. U. 100 F. J 25 (approx.) Blend S. S. U. and 20% 2600 73 0.12..- 270 33 0.29 0.02 0.21 73 Do. S. S. U. 100 F. V. I. 45, Av.

vis. S. S. U. 100 F.

fairly rapidly under the conditions of paper mill and. similar operations with a relatively very viscous oil. The use of either oil component alone, or of a single oil of intermediate viscosity, is much less satisfactory.

The following results were obtained in tests when the bearings were operated at 250 F., with a surface speed of 33 ft. per minute. The greases were of soda soap base. Consumption The compositions tested in Table II are given in the following examples.

55 EXAMPLE C 60 rate and the lubrication was very poor, as indicated by the thickness of the oil film on the joura d lea a e a expressed as pounds p 100 nal. The leakage was low (0.025 lb. per 100 hours per bearing. hours).

TABLE I Grease Composition Bearing Test Results M' lOil CTotal E t' 111618 OIlSllmD- V8P0l8 1011 Per Cent Viscosity tion Leak- (Per cent of gggg Soap SUS at age total Journal 210 F. consumption) A 26 40 0. l6 0. 03 71 Pool. B 16 127 0. 14 0. l2 12 Excellent.

1 Unsatisfactory.

EXAMPLE D The grease indicated at D in Table II was prepared from a highly viscous mineral oil of 3300 S. S. U. at 100 F. This lubricant showed very little evaporation, about 7% under test conditions, and gave excellent results from the standpoint of lubrication. The leakage was high (0.10 lb. per 100 hours) and this was considered unsatisfactory because of safety hazard and lack of cleanliness.

- EXAMPLE E Grease E of Table II was prepared from a mineral oil made by blending the oils used in greases C and D, Examples C and D above. Such a grease which contained a blend of relatively very light and very heavy heavy oils showed an evaporation of about 60% and gave very good lubrication. This grease was considerably superior in evaporation rate and leakage characteristics to a grease prepared from an oil of the same overall viscosity but of relatively narrow boiling range as in the next example. The blended oils from which the grease was prepared had a blended viscosity of about 360 S. U. S. at 100 F. A general range of 125 to 500, preferably 150 to 500 S. U. S. at 100 F. is considered desirable for paper mill bearing lubrication, and for comparable uses at 200 to 275 F. but the overall viscosity may be somewhat higher if the viscosity index of the blend is fairly high. A more usual preferred range for overall viscosity is between 150 and 400 S. S. U. at 100 F.

EXAMPLE F Grease F of Table II was prepared from a narrow cut oil of 350 S. U. S. viscosity at 100 F. and tested under the same conditions as the lubricants described above. In this case, however, the evaporation rate of the oil was considerably lower, about 33 as compared .with 60% evaporation of the oil of Example E. It is evident that the mixture of high and low viscosity oils is definitely superior to a narrow boiling oil of the same viscosity range. The outstanding feature of this invention is the discovery that evaporation must be somewhat higher if leakage is thereby reduced without substantial loss in lubricating effectiveness. This requires substantial proportions of an oil that evaporates fairly rapidly at the operating temperature.

The above data indicate that in order to provide the best lubrication as well as to secure minimum leakage it is desirable to prepare greases from mixtures of relatively very high and very low boiling range oils to control consumption, evaporation and leakage in actual service.

EXAMPLES G, H, .T

Grease G was made according to a prior art formula, of the ingredients indicated below. Greases H and J were made of blends of 45 viscosity index oils of 100 and 2600 S. S. U. viscosities respectively at 100 F. All three oil blends have overall viscosities of about 400 S. S. U. at 100 F. All had viscosity indexes of about 45, all three greases resulting therefrom had about the same hardness (penetration) and all gave good lubrication. The grease G, however, leaked excessively. Grease H was satisfactory in this respect. Grease J was outstanding. It is interesting to note that the bearing surface of the grease block hardened somewhat in each case, due to contact with the hot journal. Thus grease G hardened from 70 to 39 units of penetration, grease H from 76 to 43, and grease J from 73 to 35. Hence the only significant difierences were in leakage Formula, per cent by weight G H I I W. G. Rosin Animal Fatty Acids. Cottonseed Fatty Ac Sodium Hydroxide l Mineral Oil (100 v./l00: 5 V. I.).. Mineral Oil (214 v./l00: 45 V. I.) Mineral Oil (900 v./100: 45 V. I. Mineral Oil (2600 V./l00: 45 V. I.)..

As indicated in Table II, greases E and F were compared at a temperature of 250,F., operating under a bearing speed of 33 ft./min. The grease E prepared by blending oils of 100 and 3300 S. S. U. viscosity, respectively, showed 47 evaporation. The leakage was 0.14 lb. per 100 hours. On the other hand, grease F under these test conditions showed only about half as much evaporation, 23%, with similar lubricating ability. The leakage was much higher in this case, being 0.22 lb. per 100 hours which, as previously noted, is highly objectionable.

Comparing grease G with greases H and J,-it will be noted that grease G was composed of a blend of lighter and heavier lubricating oils. The light oil was not light enough and the heavy was not heavy enough, however, for o'ptimum:performance. The light oil should have a viscosity below about 125 S. S. U. at 100 F. for service at temperatures of 200 to 275 F. The heavy"component should be much more viscous, preferably above 2000 S. S. U. at 100 F.

In all the above cases, sodium soaps of the common fatty acids (predominantly stearic acid) were employed. Sodium soaps of the C12 to C24 aliphatic carboxylic acids, preferably those which are predominantly saturated, are normally used for reasons of economy.

The relative proportions of high viscosity and low viscosity oils may be adjusted to secure the average viscosity desired in the final product. In general, proportions of about 3 to 6 parts by weight of light oil (viscosity to 125- S. U. S. at F.) with 1 to 6 parts of heavy oil (about 2000 up to 5000 or more S. U. S. at 100 F.) appear to be most useful. These limits may be exceeded in exceptional cases; for example, for very high operating temperatures. The soap content may vary from about 8% to as much as 40% by weight of the total composition. Proportions of 10 to 25% are normally preferred for use in paper and textile mills and the like where operating temperatures are of the order of 200 to 275 F.

It will be understood that various conventional additives such as antioxidants, tacking agents, corrosion inhibitors, extreme pressure agents and the like may be added if desired. The expression mineral base oil, in the claims is intended to cover petroleum oils which include minor proportions of such conventional materials.

The present application is a continuation-inpart of our copending application Serial No. 55,017, filed October 16, 1948, which became abandoned on December 26, 1950.

What is claimed is:

l. A block lubricating grease composition for high temperature operation consisting essentially of about 3 to 6 parts of mineral lubricating oil of viscosity between 80 and S. S. U. at 100 F. and 1 to 6 parts of mineral lubricating oil of viscosity between about 2000 and 5000 S. S. U. at

7 100 F'., said oils being blended to give overall viscosity of 125 to 500 S. S. U. at 100 F., and 8 to 40% by weight, based on the total composition, of soda base soap.

2. A brick lubricating grease composition consisting essentially of 3 to 6 parts of mineral oil of about 80 to 125 S. U. S. at 100 F. and 1 to 6 Parts of a viscous mineral oil of about 2000 to 00 S. U. S. at 100 F., said oil mixture being thickened to a still grease consistency with at least 8% of soap.

3. A block grease lubricant composition consisting essentially of light mineral base oil of about 100 S. S. U. viscosity at 100 F., blended with a heavy oil of about 2600 to 3300 S. U. S. viscosity at 100 F., said blend having a blended viscosity of about 300 to 400 S. U. S., and being thickened to a hard grease consistency with about 11.5% by weight, based on the total composition, of sodium soaps of C12 to C24 aliphatic fatty acids.

4. A block grease lubricant composition consisting essentially of a blend of mineral base lubricating oil of about 80 to 125 S. S. U. viscosity at 100 R. and an oil of about 2000 to 5000 S. S. U. at 100 F., blended in proportions to' give an overall viscosity of between 150 and 400 S. S. U. at 100 F., and to 25% of soda base soap to thicken said oil to a hard grease consistency.

5. A block grease composition for high temperature service, consisting essentially of a blend of two relatively very light and very viscous mineral oils, said light component being relatively volatile at operating temperatures of 200 to 275 F., so as to substantially evaporate in a journal bearing without leakage, said light component having a viscosity not greater than 125 S. S. U. at 100 F., said viscous oil haw'ng a viscosity of at least 2000 S. S. U. at 100 F., the overall oil blend having a viscosity between 150 and 500 S. U. S. at 100 F., and enough soda base soap to thicken said oils to a stiff block grease consistency.

6. Composition according to claim 5 wherein to of the blended oil has'a viscosity of about and 20 to 50% has a viscosity of 2600 to 3300 S. S. U. at 100 F.

LORNE W. SPROULE; LAURENCE F. KING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,966,821 Kaufman July 17, 1934 2,055,795 Kaufman et al. Sept. 29, 1936 2,295,189 Swenson Sept. 18, 1942 2,394,790 Liehe Feb. 12, 1946 2,413,121 Swenson Dec. 24, 1946 2,442,828 Smith et al. June 8, 1948 2,455,892 Fraser Dec. 7, 1948 2,457,582 v McCarthy Dec. 28, 1948 

1. A BLOCK LUBRICATING GREASE COMPOSITION FOR HIGH TEMPERATURE OPERATION CONSISTING ESSENTIALLY OF ABOUT 3 TO 6 PARTS OF MINERAL LUBRICATING OIL OF VISCOSITY BETWEEN 80 AND 125 S. S. U. AT 100* F. AND 1 TO 6 PARTS OF MINERAL LUBRICATING OIL OF VISCOSITY BETWEEN ABOUT 2000 AND 5000 S. S. U. AT 100* F., SAID OILS BEING BLENDED TO GIVE OVERALL VISCOSITY OF 125 TO 500 S. S. U. AT 100* F., AND 8 TO 40% BY WEIGHT, BASED ON THE TOTAL COMPOSITION, OF SODA BASE SOAP. 